With a heritage that harks back to the early Twenties, Jaguar is one of UK's oldest automobile marques still in business. As well being famous for several iconic sports cars such as the XK120, E-type and XK8 along with its many successes in international motorsport, it also has a reputation for producing elegant, luxurious and powerful saloons. These have included the Mk VII, Mk 2 and Mk X, plus eight generations of XJ, all of which set a new standard for their performance, ride and comfort. Launched in 1986, the fourth XJ model - internally known by Jaguar as the XJ40 - not only had a new and more modern design than its more traditional predecessors but also featured an innovative, and at the time class-leading, specification that included a clever onboard diagnostic system. However, never a car without issues - the XJ40's gestation alone took well over a decade - its many reliability issues would have a long lasting impact on both its reputation as well as Jaguar itself.